Seven-times world champion Lewis Hamilton expressed concern about Red Bull's continued dominance and questioned whether Mercedes could close the gap next year after Formula One's Abu Dhabi season-ender on Sunday.
Red Bull's Max Verstappen took a record 19th victory in 22 Grands Prix, and his 21st podium of the year, as his team closed out the most dominant of campaigns, winning all but one of the races.
The manner of the Dutch driver's final victory of the season provided little reassurance for those hoping for closer competition in 2024, with Verstappen 17.993 seconds clear of Ferrari runner-up Charles Leclerc.
The once-dominant Mercedes finished second in the constructors' championship but with less than half the points scored by Red Bull.
"It's not been a great year. There's not a lot to take from the year in general," Hamilton told Sky Sports after finishing ninth with teammate George Russell third.
"The fact that I survived it, probably that's about it.
"At this moment I don't really know," he added when asked whether he believed Mercedes could challenge with next year's car.
"For Red Bull to win by 17 seconds in the end and they haven't even developed their car since August is definitely a concern.
"But we've learned a lot about the car and it's just down to the team now. They know what they need to do. Whether or not we will get there, we will see."
Team boss and co-owner Toto Wolff sounded more optimistic, despite Mercedes ending a season winless for the first time since 2011.
"This day feels like you've won and that's great. We've got to be happy about that but also as a racer you want more, but today we won," he said of the battle with Ferrari for second overall.
"We have a gap to the leaders, but the two [Mercedes] teams in Brackley and Brixworth [engines] are so motivated, we have so much good things in the pipeline, so much new things.
"I am in a really good place to see what's coming together. We've got to take momentum from here and take that momentum into the factories."